Do you scramble for a Halloween costume the afternoon of Oct. 31 every year? These delivery startups want to help – and, in the process, gain some much-needed attention for themselves.

Instacart, WunWun and Postmates are all adding on-demand costumes to their inventories this Halloween. The delivery startups don't usually offer items like horse masks and witch's hats, but in the spirit of the season and in the hopes of gaining new customers, Halloween has brought about some spooky limited-time offerings.

“For many people, going from store to store to find the perfect costume can be a huge hassle, and traditional online ordering can mean waiting days or even a week for delivery,” Instacart's operations and growth manager Stephen Klein said in a statement. “And many people who need costumes for parties wait until the last minute. Now Instacart customers can browse our selection, pick what they need, and have it all delivered to their home or office within an hour.”

Normally, Instacart delivers groceries. However, this week the service partnered with local merchants to sell costumes in Seattle, with the promise of same-day delivery.

Another service called WunWun, which offers free delivery of almost anything you can think of to customers in New York City and San Francisco, has expanded "everything delivery" to encompass Halloween costumes. Postmates is doing the same, adding a Costumes On-Demand store in the app from 10 a.m. to 6 p.m. until Oct. 31 in San Francisco, New York City and Chicago.

Of course, Halloween specials aren't unique to the delivery industry. Uber is giving free rides, as well as a $100 Uber credit for the best Uber Jack-o-lantern posted on Instagram. Chipotle is famous for its $3 Boo-ritos, and plenty of other restaurant chains traditionally have their own deals for trick-or-treating children and hungry parents.